A generalized apparatus for removing oil from chips after they are fried is shown schematically in FIGS. 1 and 2. As shown in FIG. 1, the chips 12 are fried in an elongated vat of oil 10. The chips are caused to flow from left to right, as shown in FIG. 1. As the chips approach the end of the vat 10, they are picked up by an endless belt conveyor 14, which transports them through interchamber 16 and then through de-oiler apparatus 20. As shown in FIG. 1, the chips tend to arrange themselves in a "shingled" arrangement in which they are generally overlapping and standing on edge, similar to closely spaced dominoes.
As shown in FIG. 2, the de-oiler 20 is basically an annular chamber through which the chips travel (into the page in FIG. 2) on the conveyor 14. A series of blowers 22 are arranged along the length of the de-oiler 20 to circulate a steam atmosphere through the de-oiler 20, guided by turning vanes 21. As the steam passes through the bed of chips distributed across the width of the conveyor 14, it removes excess oil from the chips. The shingled arrangement of the chips facilitates circulation of the steam through the bed of chips and, hence, improves oil removal. (The belt of the endless belt conveyor 14 must be relatively porous or permeable for the steam to circulate through the chamber.) The removed oil is collected in oil collector trough 28 and is either filtered and reused or is discarded. The de-oiler also includes a de-mister 24, which separates oil from the steam, and a heat exchanger 26, which heats the steam to the desired temperature
At the end of the de-oiler, the chips tumble off of the conveyor 14 into a rotary air lock 30 (FIG. 1). The airlock 30 functions like a revolving door, receiving chips via upper aperture 32 and dispensing them through lower aperture 34 onto take-away conveyor 36 while generally keeping the de-oiler sealed from the ambient atmosphere. This is generally required to contain the steam within the de-oiler-unit and to maintain a low-oxygen environment in the de-oiler unit.
As further shown in FIG. 1, the upper inlet wall 44 of the de-oiler has generally been provided with a rounded flow diverter 46 on the inside surface thereof, extending into the interior of the de-oiler, and the lower inlet wall 45 has been provided with a rounded flow diverter 47. Similarly, a rounded flow diverter 50 has generally been provided on the upper exit wall 52 of the de-oiler 20, extending into the interior thereof and a similarly shaped flow diverter 51 has been provided on the lower exit wall 53.
The flow diverters 46 and 47 help prevent the steam-enriched atmosphere from flowing out of the de-oiler through the inlet 42. Such a high speed exit flow tends to blow the chips over and destroys the shingled arrangement, thereby hampering de-oiling flow through the bed of chips. It also inhibits transfer of the chips to the de-oiler by blowing the chips back into the fryer. Similarly, the flow diverters 50 and 51 direct the steam atmosphere into the interior of the de-oiler and help minimize loss of steam through the rotary air lock 30. Moreover, it is desirable to prevent the relatively oxygen-rich atmosphere of the fry vat region from being sucked into the de-oiler chamber 20. To this end, various additional flow control devices have been used in connection with the baffles 46 and 47, but prior to the present invention, they have not worked as well as would be desired.